DR George wrote earlier:
"
In my DVD player: "The Incredibles" I also got this from the library...unfortunately, it's full-frame. When I buy it, I'll get the widescreen version."
Definiitely you will want the widescreen version since it was composed in the wide-wide 2.35:1 aspect ratio (akin to Cinemascope and Panavision). Very few animated films of any kind have ever opted for this widest of formats.
I'm assuming Pixar didn't pan and scan the original film to get the full frame release but rather recomposed it in the computer for full frame monitors. I know they did this with A BUG'S LIFE and some others of their films, so the full frame will probably be OK. But seeing that wide image done so beautifully is really an awesome experience.